Why I use rated range, not percentage SOC

Why I use rated range, not percentage SOC

A nit subject but...

I had a friend that swears by just using % SOC on the front display. So, I tried it for a while and didn't find
it better or worse, just different. And then I realized why thinking in '% SOC' is a donkey of an idea.

Now that we have a lot of cars with 60kwh to 100kwh batteries if we all learn to monitor
range via %SOC rather than rated range we are screwed when we get into another Telsa with a different
size battery, or into another EV.... your intuition will be messed up.

If you know the rated range of a car you know where stand a lot better than just being told the % SOC.
So, unless you think you are going to own the same car with the same size battery for the rest of your
days you might want to stop using % SOC.....

I would prefer Tesla change ALL displays to rated range..e.g. Nav report, trip planner graph, etc.

I have a good idea how rated range drops with headwinds, rain, temp, etc and I think that intuition will
be pretty transferable to any EV for which I know the current rated range...better than % SOC for sure.

Ok, so can somebody that uses % SOC tell in more detail why they like it?

Stiction | 09. lokakuu 2016

Sigh. I hate nine mile wide text input boxes...can't stop hitting automatically

Stiction | 09. lokakuu 2016

hitting return automatically

tes-s | 09. lokakuu 2016

Somehow we managed for 100 years with fuel gauges in our cars, and most phones show %SoC.

Not really that big a deal.

I like it because when I am at a supercharger I can see the kW charge rate on my phone app to see if there is a problem with the charging rate.

UnshodBob | 09. lokakuu 2016

I use both. I keep my dash display on miles. When I am using nav on unfamiliar trips, I keep an eye on %SOC on the trip screen in the energy app. While charging, I enter the next destination and make sure I have 10-20% buffer before leaving the supercharger.

If I was in a Tesla with a different battery size, I think my method would work just as well. Not sure about other EVs.

It's like six of one and a half dozen of the other. I think of 1% as about 2 to 3 miles, depending on how windy or cold it is out. Any more than 3 is frosting on the cake. :)

Tropopause | 09. lokakuu 2016

Good point about the different battery/vehicle scenarios.

Here's why I like SOC:

1% = 1%

Here's why I don't like Rated Range:

1 rated mile does not equal 1 statute mile.

jordanrichard | 09. lokakuu 2016

I think going by SOC is better for those who have had their cars for a long while and have developed a sense of how far "x" % is in terms of miles.

Even though I have driven 54,000 miles already, I usually have it set on miles. Simply because I know how many miles away something is, not what % away it is. I also keep the "Trips" display next to the speedometer. Since the rated miles displayed is based on an avg 278 wh/mi, the closer my usage is to that 278, the more accurate the rated miles are.

Stiction | 09. lokakuu 2016

@jordan richard: I have a very good sense of how to derate rated miles to real miles the same as you have for %SOC.

But one is scaled to battery capacity and one is not, so your 'sense' you've developed is rubbish in a car with a different size battery.

@tropo: exactly. A RATED MILE is a unit of energy, that has been taking from one data point (65 mph blah blah) for that particular make of car. It tells you a lot right off the bat...not actual miles, for that you need to derate based on have to learn to do that in any EV and with any units

Stiction | 09. lokakuu 2016

@jr: meant to say 'rubbish in a car with a different Wh/mi'

in an 70-85-100D you are well trained since the Wh/mi is the same.

Boonedocks | 09. lokakuu 2016

100% use SOC %. I have a constant readout of "miles remaining" in my BMW 7 and it changes constantly. Turned off miles remaining in my Tesla after one week of ownership. Never turned SOC - miles remaining back on sense then.

Ruby110 | 09. lokakuu 2016

I use energy so I won't obsess over rated miles variations. If the trip prediction were changed to rm, I would reconsider. I hadn't considered the new vehicle issue but I figure I can make the adjustment quickly when our Model 3 arrives.

Boonedocks | 09. lokakuu 2016

I have also had some conversations with fellow Model S owners that don't frequent the forums so I will throw in a common theme for them as well:

The reason most of them prefer the SOC % is that they don't freak out when traveling and it says say 8-15% upon arrival but totally spaz out when they tried miles and saw ~16-25 miles upon arrival. Just a mind thing but they are much more comfortable with a % vs miles displayed when things get low while traveling ¯\_(ツ)_/¯

Haggy | 09. lokakuu 2016

Ideally, I'd like to see projected miles. The car calculates it anyway so it's not as if it would be a big deal to make it an option.

Tropopause | 09. lokakuu 2016

Agree with Haggy.

adrenalinejunkie | 09. lokakuu 2016

% SOC combined with projected miles based to "empty" is exactly how I've managed for decades now across many different cars with different sized tanks and different fuel economies. I just wish Tesla would show projected miles in the dash when I have the energy display up. It shows it on the big screen - why not the dash display? Virtually every ICE car can put it in the dash and it's the most useful piece of info.

alex.sanders | 09. lokakuu 2016

For me I used % initially to combat range anxiety. Very quickly I discovered that relying on rated range was going to get me stranded. Besides everything seemed more normal with a %gauge just like my old fuel gauge; somehow I am more comfortable running the car 3-4 days without charging. When I need an estimate of remaining km or miles I open the energy app which gives me a more accurate picture of remaining KM or miles than the rate range does.

eush | 10. lokakuu 2016

I prefer % over rated range mainly because 1% is 1%. I suppose if i upgrade in the future i will just get used to the new battery in time. I personally don't like rated range because it always changes.

JayInJapan | 10. lokakuu 2016

Since I can see the % remaining from the battery bar, I use the Typical range setting. I find it far easier to predict my remaining range. If I'm dealing with inclement weather, I'll throw the Energy app up as well.

SUN 2 DRV | 10. lokakuu 2016

I agree with the OP...

I use Rated Miles and I wish the charge screen showed kw when in that mode.

% SoC seems pretty useless to me. I'd like to see kWh instead...

Energy or miles are each meaningful and useful engineering quantities. %SoC is an oversimplification and obfuscates the actual meaning of that number... Percent of WHAT? It's percent of kWh or Rated Range... so why not show the actual rated range or kWh value?

UnshodBob | 10. lokakuu 2016

@Sun 2 drv - I think it is meant to emulate the old gas gauge from ICE age vehicles.

DonS | 10. lokakuu 2016

I don't like rated miles because it is WRONG. I'd be stranded regularly if I depended on that number.

Darthamerica | 10. lokakuu 2016

I use %SOC because the rated range assumes specific conditions that are hard to reproduce in uncontrolled environments. For example you've got a commute that usually consumes 10 miles of rated range. Now the weather changes dramatically and you end up actually using 1.2x the rated miles as reported before. Not a big deal during a short trip assuming you have the range but on longer trips or between charging it could misleading you into thinking you can go further than you can. Whereas with %SOC, I always know that as long as I keep a certain amount of battery capacity, in covered across a wide range of conditions. I just think it's less likely to cause me to run out of energy or having to make an unplanned charging stop.

mjt.private | 10. lokakuu 2016

What's the point of this thread?

Do what you want, but let me use % in my car. They only Tesla I ever drive. Stop trying to tell me how to live.

The reason people say to use SOC is because of the dozens of posts complaining that the rated mile is misleading.

SOC stops you guesstimating a range via a dozen parameters in your head, when the Energy app will do the job infinitely better. But SOC does give you n instant guide as to how soon you are going to have to charge.

Here's a thing: it's 10% to my nearest SC from my house, and 15% back, and there is the problem in a nutshell.
[PS not suggesting I use my SC when I can charge at home!]

Darthamerica | 10. lokakuu 2016

Rated miles = range at the time under ideal conditions. %SOC = actually energy in the battery. Seems to be a more reliable method of estimating range and planning in safety buffer against unexpected additional power consumption.

UnshodBob | 10. lokakuu 2016

I believe they both count down to the same number. :)

Tarla's Driver | 10. lokakuu 2016

I use rated range. We normally get just a hair better than rated range, so it works great for us. If it's super hot or cold, I watch for having a few extra percent. If we put bicycles on the roof rack, then I'll want at least 3 miles for every 2 that I'm actually driving. I also watch the difference between the rated range and the miles to my destination to see how things are going. If the number of extra miles is dropping, then I can use the rate of change to tell me if I'm alright at my current speed.

Though with the trips I've taken, I've only had to be really careful a handful of times. Twice I pulled into a Supercharger with only 10 miles left, only one of which I slowed down at all to extend the range (and even then only a little bit).

Mike83 | 10. lokakuu 2016

I don't understand why it is so difficult. There are many options like Navigate to _________, then open Energy chart and click on Trip. It shows how much battery is left at destination and adjusts for speed. Or use the E graph itself which lists 5, 10 or 30 miles for average or instance miles left.
Why not use the features as they are simple?

JAD | 10. lokakuu 2016

I think I need a new battery, the rated range dropped, is something wrong, did I supercharge too much, oh wait, still charges to 80% as always, never mind...

Use what you like, 95% of the time, the battery never gets low enough for me to care enough to even look, it is always charged for way more than my daily usage.

I think % causes less stress daily, and rated is more useful when nearing 0, but they are both just psychological, the car goes the same distance with either display...

djmichaelmayhem | 10. lokakuu 2016

I like the % SOC personally and I have an P85D. I get the different pack size argument but I guess it's like the cell phone comment for me. As well, you can always leave the energy app on the bottom half of the main screen to see rated or estimated range, wich I do.

TaoJones | 10. lokakuu 2016

I use % exclusively. The concept of a rated mile means little to me either locally or during longer trips.

SUSTEKI.TOKYO.JP | 10. lokakuu 2016

It's it great to have the option to fit your needs.? ;-)

Darthamerica | 10. lokakuu 2016

Again, the problem is that rated miles is nothing more than the %SOC represented as miles of range under very specific conditions. However since you are very unlikely to duplicate the conditions used in the EPA testing, it can be misleading.

I know when my car says I have 230 miles of range, I may only get 180 in reality. Why would I want to mislead myself or waste time trying to figure out if using the HVAC or 40F temps are going to dramatically shorten my range? Instead, just watch the %SOC which tells you how the battery is doing based on actual driving style and conditions.

If the displayed range could be displayed based on actual energy consumption(including estimates based on the route chosen by the nav), weather, windows up or down, # of passengers + cargo in weight, HVAC usage, wheels/tires, tire pressure, elevation, on board systems energy consumption, wind resistance and minus battery degradation, then it would be more useful. Otherwise it's just an arbitrary guesstimate that's more often than not inaccurate. It's much more useful to display remaining current %SOC.

martin | 11. lokakuu 2016

"1% = 1%"

How true.
But there is one question that many people overlook when talking about %ages, namely "% of what?".
In 70 kWh battery "1%" means something different than in a 100kWh battery. When only looking at %SOC all battery sizes charge in roughly the same time from 10% to 90%. But are they charging at the same speed?

martin | 11. lokakuu 2016

And to answer my own question:
No because a 100 kWh battery gets you a longer way than a 70 kWh battery at the same % SOC.

T90KWH | 11. lokakuu 2016

To me, this is a kinda weird thread. Use whichever you like, use both (sequentially) or both (concurrently). Who gives a [insert worthless item]? I have rated miles on the dash and % remaining in the Energy App, and I'm just about (only just, mind) clever enough to be able to use either to work out if I need to charge. We are not a homogenous group - some will like one thing, and some another, and really we don't have to justify it to anyone else.

Silver2K | 11. lokakuu 2016

I use rated miles and energy app when it gets hairy (that's what she said). the way I see it, the % setting is like a container of miles that is a mystery which is not going to be very accurate when it's at 5% or lower (IMO). I have cut it close many times and think it's important to know how many miles are left on the battery, not %. I have gone down to 6 miles left on battery while driving. These pictures naturally show 10 miles because I took them while parked. this is when I first got the car and travelled to a job in watertown from Syracuse with over 200 miles left on battery. The location in watertown is around 67 miles away and the temp was much lower in watertown. I did make a couple of stops on the way to resolve some issues at different locations. the cold weather ate up lots of electrons as you can see (since last charged) and I do normally drive at 74 mph, but drove 65 on the way back.

Silver2K | 11. lokakuu 2016

ps: at that time, there were no SCs in watertown and the dealers would not let me plug in.

Darthamerica | 11. lokakuu 2016

All other vehicles rely primarily on a fuel indicator. I don't see why using the %SOC is any different.

UnshodBob | 11. lokakuu 2016

If you are in an unfamiliar area and a highway sign says there's a town 13 miles away where your hotel with HPWC is, and you have 5% SOC remaining, can you go those 13 miles? Maybe displaying rated range would be better? Assuming not frigid temps or uphill/downhill all the way. I'd be using both energy app trip display in % and showing rated range on dash. Thats my 2¢.

martin | 11. lokakuu 2016

The milage left in the Tesla is far more accurate than a fuel gauge and this accuracy would be wasted in %age. On this one I agree with UnShodBob..

Tarla's Driver | 11. lokakuu 2016

Having a percentage is awesome. If I know my destination is 64% away, then I can look at the percentage of the battery left an know whether I have to stop and charge before I get there. What could be easier?

Silver2K | 11. lokakuu 2016

the % has a different meaning in 60, 70, 75 an d so forth.

In my p85+ 100% means each % is .75kWh (I believe 85's have to 75kWh and the rest is brick protection) correct me if I'm wrong here

assuming a 60 is .60kWh per % (just using max as an example, I know 60's don't have access to 60 kWh)

this can be confusing to some because what that % means when it comes to miles remaining. It only makes sense to have rated on the screen to me. And that % mile value changes with weather.

Silver2K | 11. lokakuu 2016

I believe 85's have "access" to 75kWh ...

UnshodBob | 11. lokakuu 2016

@Tarla's Driver - I know the post office is about 8 miles away. Phoenix is about 320 miles away. Los Angeles is about 60 miles away. I knew these numbers before I got my Tesla. Should I convert to % now? The highway signs show miles, not %. If I got a 25% bigger battery, all the % numbers would change, but not the miles. One mile is 5280 feet, no matter what. How far is 1%? Mic drop. :)

SUN 2 DRV | 11. lokakuu 2016

Unshod +1, +1 and another +1 for your various points :-)

And as usual Haggy has the best idea, why not offer to display Projected Miles?

SoC by itself tells me nothing. I agree Rated Miles may not be perfect but at least I can more easily estimate my likely actual remaining range if I see my Rated Range (in miles) and then derate it by 20-30% for my lead foot.

If I start with SoC then to estimate my remaining range I need to multiply the %SoC by my battery size, times my % of usable capacity, times my wH/mile, divide (or is it multiply) by 1000 to accommodate the units of kWh for battery and wH for efficiency..... and all of that to get my remaining Rated Range!!! which I then have to derate for temps, winds elevation etc anyway.

Yes Rated Range is not perfect, for for me %SoC is even less useful... You're in trouble when either one of them goes to 0. :-)

UnshodBob | 11. lokakuu 2016

@SUN 2 DRV - thanks times three! :)

My car shows projected miles at times as high as 999 (max displayable value?) which is obviously impossible. I don't know when projected would convey good information. It's like "at most" instead of "at least" miles. Double the percent is 500wh/mile. That might be a valid minimum.

Your last line echoes my earlier post:

UnshodBob | October 10, 2016
I believe they both count down to the same number. :)

Silver2K | 11. lokakuu 2016

screw that!

-1.5 to unshod shift +1.5 to me for proper explanation!

+.5 unshod - For not having gum stuck to his feet at the end of the day!
+1 unshod - For a second explanation and agreeing with me


UnshodBob | 11. lokakuu 2016

At least I got my 1.5 back :)

And you're right, no gum on my soles. :)

UnshodBob | 11. lokakuu 2016

I see 6 of mine and 3 of yours @Silver. You get +2 for the photos. But who's keeping count? :)

Silver2K | 11. lokakuu 2016


TaoJones | 11. lokakuu 2016

Not to mention that unless remaining miles are updated instantaneously, unless unless you consume exactly 279W/h, the number is not accurate.

A percentage, meanwhile, is accurate no matter what.

I would prefer that the granularity be increased one decimal place once the percentage drops below 3%.

But, since that's for edge cases anyway, as important as they are, I would still MUCH RATHER prefer they fix the disaster that the UI/UX has become for Nav and media management and pane management in v8.x first. What a mess.